The art of the present invention relates to musical instrument bridges in general and more particularly to a musical instrument bridge which efficiently transmits string energy into an instrument body yet maximally isolates individual string energy from other strings on the instrument.
Conventional stringed musical instruments such as guitars have one or more strings affixed or mounted along the length of the instrument. Said strings typically pass over a nut distal the musician and are fixed and tensioned by a tensioning adjustment, tuner, or tuning pegs at a first end. At a second end, said strings pass over a bridge and are anchored to a bridge plate or the instrument body itself. The vibrating length of the string is between said nut and bridge with said bridge typically having parallel adjustment with the string axis in order to shorten or lengthen said vibrating length. Vibrating length adjustment is necessary in order to achieve perfect intonation. That is for the western tonal system, an octave (i.e. twice the fundamental vibrating frequency) represents 12 half steps or logarithmic chromatic frequency divisions between notes of equivalent type. (e.g. A to A, C to C, etc.) Especially for fretted instruments such as a guitar, depression of a string located at the 12th fret position away from the nut must produce a perfect octave relative to an open string. This intonation adjustment is only achievable if the vibrating length is adjustable since intonation is dependent on string mass and elastic properties.
For playability ease and optimization, it is desirable to minimize the musician imposed force between a string and the fretboard or neck in order to create a desired note. This is typically known as an easy “action” and means that the musician minimizes his or her effort during play. Unfortunately, too easy of an action, i.e. a string positioned very close to the fretboard or neck, creates a “buzz” or nonlinear resonance. Conventional stringed musical instruments thereby require adjustment of the string height relative to the neck or fretboard. Since said nut is usually affixed to the instrument, optimal string height is typically achieved by adjusting the bridge height.
Prior art bridges often provide bridge height adjustment via one or more semi-pointed setscrews threaded substantially perpendicularly through a saddle and seating or bearing upon a metal base plate attached with the instrument body. This prior art configuration transmits string vibration into the instrument body via the tip of said setscrews. Unfortunately, the acoustic impedance mismatch between said setscrew point and said plate and the frictional movement between the aforesaid fails to achieve high quality string tone and sustain. That is, without a solid connection between a string and the instrument body, the string energy attenuates rapidly and does not readily transmit into the body. The resulting poor tonal quality and sustain is especially noticeable for low frequency notes such as found in bass guitars. This is especially true for a bass guitar which often relies upon body and neck resonance for high quality note representation.
The aforesaid prior art bridge systems utilize said base plate mounted via screws to the body of the instrument without an integral attachment there between. Upon this base plate are mounted said bridge saddles that are aligned with and support each string. Unfortunately, the prior art often retains the string via this plate whereby string force tends to pull said plate away from the instrument body. This force further limits the energy transmitted to the instrument body, especially when a minute gap forms there between. That is, the string force prevents a solid connection between the string and instrument body. Variations of the prior art mounting methods are shown and described in U.S. Pat. No. 4,208,941 entitled Adjustable Bridge Saddle by Wechter with issue date of Jun. 24, 1980, U.S. Pat. No. 5,285,710 entitled Adjustable Bridge for a Stringed Musical Instrument by Chapman with issue date of Feb. 15, 1994, and U.S. Pat. No. 5,295,427 entitled Bridge for String Instruments by Johnsen with issue date of Mar. 22, 1994.
Said prior art bridge systems also generate undesirable fundamental or harmonic interaction between the strings on a multi string instrument. Since the bridge comprises a continuous metallic base plate of different acoustic impedance than the wood, polymer, or composite material of the body, acoustic energy is reflected from the interface and retained within said bridge. Since the metallic base plate structure is not highly attenuating, said energy is transmitted to other strings retained by said base plate and induces unwanted vibration thereon.
The present art overcomes the prior art limitations with a uniquely constructed and body attached bridge apparatus which minimizes string energy loss and maximizes acoustic energy transmission into the instrument body. Unlike the prior art, each bridge piece of the present art is a solid construction which is secured to the instrument body and thereby maximizes tonal purity and sustain and minimizes harmonic interaction between the strings.
The present art not only provides the aforesaid benefits via a string support assembly but further utilizes a unique string retention assembly whereby acoustic separation and body transmission is assured. That is, the string retention assembly of the present art is integral with and internal to the instrument body. This arrangement provides an acoustic energy feed directly into the body of the instrument for any energy transmitted past the string support assembly via the strings.
Accordingly, an object of the present invention is to provide an optimally coupled string instrument bridge and method of manufacture which maximizes acoustic energy transmission into the body of the instrument.
Another object of the invention is to provide an optimally coupled string instrument bridge and method of manufacture which maximally isolates fundamental and harmonic vibratory interaction between strings on the instrument.
A further object of the present invention is to provide an optimally coupled string instrument bridge and method of manufacture having strings secured to the instrument body and not the bridge whereby said bridge is not forcibly pulled away from said body.
A still further object of the invention is to provide an optimally coupled string instrument bridge and method of manufacture which provides all of the length and height adjustment features of a conventional bridge without the undesirable coupling and transmission characteristics.
A yet further object of the invention is to provide an optimally coupled string instrument bridge and method of manufacture which minimizes the acoustic impedance mismatch between the bridge assembly and the instrument body.